1. Field of the Invention
The present invention relates to a device for measuring an average time period of people staying inside a building such as department stores, exhibition halls, etc. (hereinbelow, this time period is called a "mean staying time").
2. Prior Art
The device described in Japanese Patent Application Laid-Open (Kokai) No. 61-7675 is an example of an automatic device that measures the mean staying time.
As shown in FIG. 4, this device is made up by a detection means 1 and a processing means 2. The detection means 1, that comprises an entry-detector 11 and an exit-detector 12, is installed at an entrance/exit of a building (or a particular "establishment") and detects persons entering into and exiting out of the establishment. The processing means 2 processes the detection signals supplied from the detection means 1. The device further includes a timer 4 and a memory 3, etc. which are connected to the processing means 2 along with a display 5.
In the memory 3, the time at which an entry detection signal is generated by the entry-detector 11 is stored in the order of signals generated. The detection signal is generated when a person enters into the establishment. Also stored in the memory 3 is (a) the number of times persons exiting from the establishment detected by the exit-detector 12 and (b) the sum of the time difference between when persons entered and exited in the same order (that is, the sum of the time difference between a first person who entered and a first person who exited, a second person who entered and a second person who exited, and so on). Thus, the mean staying time is calculated by dividing the sum of such time difference by the number of persons who have exited (that is, by the number of persons who have exited as detected by the exit-detector 12). The mean staying time thus obtained is displayed on the display 5.
However, in this prior art measuring device, the entry time of a large number of persons who enter into the establishment must be read individually from the timer 4 and then stored in the memory 3. This causes problems. The overall size of the measuring device needs to be large because a large capacity is required for the memory 3 so as to store all the entry time information of persons who have entered into the establishment.
In addition, the prior art device measures (and displays) the mean staying time of persons who have entered between the time the entry thereinto started (e.g. the time a store is opened) and a specific time thereafter. As a result, the mean staying time during a particular time period of interest, or the mean staying time at a specific time, cannot be obtained. In other words, even though, a true mean staying time of each of various time periods of interest can make it possible to review the relationship between the mean staying time information and the amount of sales, etc., with the conventional devices, the mean staying time data cannot be used efficiently because they cannot measure the mean staying time at a particular time period.